A complex late-winter storm will produce heavy rain for most of the region from Tonight into early Wednesday Morning and perhaps significant accumulations of freezing rain over Northern PA, as well as some severe thunderstorms in Southeastern PA.
This storm will most likely produce widespread rains of 1 to 2 inches, with 3 inches possible, and this rain combined with snow melt could cause flooding, especially on the smaller rivers and streams.
Warm temperatures and mostly sunny skies today could melt some of the snow. This melting would get that water that is on the ground into the rivers and streams before the heavy rain, and would make any flooding less severe. But, lots of the northern and western portions of the area will likely still have snow on the ground when the rain starts on Monday Night. These are also the areas that will be most susceptible to ice from freezing rain, and mixed precipitation.
The threat for freezing rain in the north looks like it could be real with very cold air moving across the upper Great Lakes Today and down into PA from the North Tonight and Tuesday. The daytime solar radiation on Tuesday may warm temperatures again in the afternoon, and may keep the icing from becoming major.
The threat for flooding over most of the region remains high, and a Flood Watch has been issued. There may also be a threat of severe convection/thunderstorms over the Southeastern corner of the State Tuesday Evening and Night.
See a Satellite Estimate of Snow Depth
See the NWS Co-Operative Observing Sites' Snow Depth Reports (once per day)
More forecast details will follow in the coming days as the situation comes into better focus. Keep a NOAA Weather Radio handy for up-to-the-minute forecasts and possible Warnings and Advisories.